Don’t let anyone tell you that delphiniums are hard to grow.
After having grown some 15,000 delphiniums over the past seven years, I believe that if you can grow iris, daylilies, or even radishes, you will have as much success with delphiniums.
The familiar blue of delphinium is now only one of the cameo colors for these stately flowers.
Red or pink delphiniums, or for a really vivid splash, orange blossoms, will give you a brand new exhibit in your garden.
Your neighbors will surely stop and ask, “Are those really delphiniums?”
Seed Or Seedlings?
If you want the judges to award a blue ribbon to your delphinium entry at your local flower show, the best place to start is with good delphinium seed.
Get the best hand-pollinated seed. It doesn’t take much more work to grow the best quality seed than to grow poor quality seed, but just compare the results!
If you want immediate bloom the first year, buy year-old plants grown from top-quality seed.
If you are willing to wait for a modest bloom the first fall and have your spectacular bloom the second year, then buy the seed. It is less expensive and, in my estimation, a lot more fun.
Storing The Seed
When you receive the seed, put it immediately in a sealed container such as a mason jar.
Screw the lid on tight and store the jar in the refrigerator until you are ready to plant the seed.
Delphinium seed stored in this way will remain in good condition for several years and has retained its germinating power for up to five years.
The same seed stored loose at room temperature loses its growing power in a matter of months.
One gardener I know stored his seed in the deep-freeze section of his refrigerator where the temperature was 5° degrees Fahrenheit above zero. Every seed germinated.
When you are ready to plant the seed, say about August 1, fill a seed flat with sifted compost, garden loam, and sand, about one-third of each.
Use no fertilizer. Fill the flat to the top. Press the soil down lightly until it is ¼” to ½” inch below the top of the flat. You can then mark off shallow rows, but I prefer to sow on flat soil.
Open the seed packet and drop a pinch of Semesan into the envelope. Shake the envelope briskly so that each seed is covered with the fungicide.
This helps to prevent the damping-off of seedlings. So now, forget you’re handling delphinium seeds and sowing them like radish seeds.
Next, cover them with a mixture of sifted compost, garden loam, and sand to the thickness of a dime.
A friend said. “You mean the diameter of a dime. don’t you?” “No,” I said. “I mean the thickness of a dime exactly.”
More delphinium seed is wasted by too deep planting than is ever killed off later by disease. Therefore, I often cover my seed with an ½” inch layer of sand.
Next, thoroughly water the seed and set it in a cool place. Keep it out of the hot August sun until germination occurs, from 14 to 21 days after sowing.
The cement floor of a garage is a good place, or a cool basement or shaded cold frame. Water the beds enough to keep them moist during germination, but avoid saturation.
If you notice signs of damping-off (the new stems or leaves falling over as though they were wilting), mix 1/2 teaspoonful of Semesan in a gallon of water in a sprinkling can and water the flat with it. This will halt damping-off.
Transplanting Pots
In about six weeks, the second true delphinium leaves will be showing. Now is the time to transplant the seedlings into 2 ¼-inch or 3-inch pots.
I sometimes use plant hands. One precaution: see that the growing tip is at the topsoil level. If this growing tip is under the soil level, further growth is greatly retarded.
You can plunge the pots into a cold frame’s soil or a row in the garden. Set the pots deep enough in loose soil so that the surrounding soil reaches the pot rim.
This conserves moisture inside the pot, producing a better plant titan if it were set on the soil level, where the wind would dry it out in a few hours.
Planting of Seedlings
I like to carry fall-sown delphiniums in pots over winter plunged in my cold frame if you are going to plant the seedlings in the garden.
Do it as early as possible to give them time to get established before cold weather sets in.
If you do not have a cold frame, the best plan is to keep your seed in the refrigerator until the following March or April before sowing.
Then you can have them ready to plant in the garden by June or July, and they will be well established before winter sets in. Such plants should bloom for you the first fall.
Winter Coldframe Care
If you can put the seedlings in a cold frame during the winter, you have nothing to do except keep them watered as necessary.
When cold weather comes, I put on a top dressing of 1” inch of sand and put the sash on for the winter.
Some ventilation may be needed if unseasonably warm weather comes in January or February.
Several hours of hot winter sun can send the temperature in a closed cold frame to over 100° degrees Fahrenheit in a short time.
Spring Planting
In spring, you are ready to plant out the delphinium seedlings in their permanent positions. Now is the time for fertilizer.
Spade the garden as early as possible, using plenty of well-rotted cow manure and a liberal bonemeal with a sprinkling of agricultural lime.
If you cannot obtain rotted manure, use compost, peat moss, or just one. Never use fresh manure if that is all you have to do with your spading the previous fall, and leave the ground rough over-winter.
Then in the spring, all you will have to do is rake the plot level, and you are all set to plant.
If you are planting delphiniums in an established garden, use groups of 3 to 5 giants spaced 2′ feet apart.
Space the groans 10′ to 15′ feet apart to the center and rear of the garden, with low-growing perennials or annuals, Phlox Miss Lingard or hemerocallis, for example, in front of them.
If you are planting in rows for cutting, space the plants 2 feet apart in the row, leaving 3 feet between the rows.
Summer Care
I save myself summer cultivation using a summer mulch of spent mushroom manure, compost, peat moss, buckwheat hulls, or the new corn-cob mulch.
Never use fresh manure, even on top of the ground. The summer mulch keeps down weeds, makes the ground less likely to hard-pack, conserves moisture, and makes a good pasture for earthworms.
When the plants are a foot high, I give them a side dressing of a complete fertilizer such as Vigoro and water it in.
Staking is a wise precaution. If I don’t stake and a sudden windstorm knocks my delphiniums over. I have only myself to blame.
After the June bloom has passed, cut the flower head off at the top of the leaves unless you wish to save your own seed.
In this case, allow a few of the lower pods to ripen. Then put on a side dressing of a complete fertilizer, watering it in.
When the second growth is 6″ inches high, the first growth can be cut to within 6″ inches of the ground. Let the stubs dry off naturally.
If you plug the hollow stem with a dab of clay will help prevent rot, as water cannot collect in the stem. The second growth will bloom in September or October.
Second-Year Blooms
The care of delphiniums over the winter is easy. They’re hardy and have been known to grow well even as far north as Alaska.
The main thing is to guard against alternate freezing and thawing without a permanent blanket of snow.
The only protection I give my delphiniums over the winter is to dust each plant with a Bordeaux mixture and then put a shovelful of sand or cinders over each plant.
The second year is when you can look for the most spectacular results from your delphiniums. Then you will be paid in full and running over for all your past care.
You will see groups in your perennial garden or rows in your cutting garden 6′ to 7′ feet high with a good 3′ to 4 ½’ feet of solid bloom in various shades of blue, lavender, purple, and white, or if you try them, those new red, orange and pink shades.
(After 20 or more years of work, A. A. Samuelson of Pullman. Washington is now ready to introduce his colorful new “West o’ the Rockies” strain.)
Many of your delphiniums will be colors, and all will be doubles.
Be sure to cut some for entry in your local flower show because you will win prizes with them.
Competition is always keen, but if you have started with a high-quality seed and followed these growing instructions, you can’t help but be among the blue ribbon winners.
American Delphinium Society
Don’t be afraid to enter your blooms in the different delphinium shows in various parts of the country.
If you become a Delphinium enthusiast and want more cultural information, join the American Delphinium Society.
The annual dues of $3.00 entitle each member to receive an annual yearbook and four issues of The Delphinium News.
Applications for membership may be sent to the Secretary of the American Delphinium Society, Mrs. Geraldine Kus. Route #1, Macedonia, Ohio.
Disease And Pest Control
Although delphiniums are easy to grow, they have their troubles like other plants. Fortunately, most of the disease and insect troubles they are subject to are easily controlled.
Mildew will sometimes cover the foliage with its white fuzz. This can be controlled by dusting with a Bordeaux mixture. As a preventive, dust the leaves after any prolonged rainy period.
Aphids or greenflies may be easily kept in check by spraying with a nicotine sulphate spray like Black Leaf 40.
Presence Of Cyclamen Mites
If you notice that the foliage and flower stems of your delphinium plants are becoming blackened and much curled and distorted, this is evidence of the presence of cyclamen mites.
These microscopic, transparent insects cannot be seen with the unaided eye. So the best thing to do when you detect “delphinium blacks” is to cut the stems off and burn the infected stalks.
Carry them out of the garden carefully, without shaking them any more than necessary. The usual treatment in the past was to spray with rotenone, but last year, a new insecticide was for this purpose.
Di-Mite was put on the market by Sherwin-Williams Co. I tried it with excellent results.
Crown rot of delphiniums has been the major problem, and there is no effective control for it.
Bordeaux Mixture to Control Pest
This often attacks a plant after the first bloom, rotting the crown to a soft pulp.
In the past, the only thing to do was to dig out the plant, replace the soil with the earth into which Bordeaux mixture or Fermate had been dusted, and replant with new stock.
But there is new hope in a product just coming into horticultural use. I haven’t yet tried it, but I intend to test it thoroughly this coming season.
I would appreciate receiving reports on its effect from any FLOWER GROWER readers who try it. This new product is Nairiphene. A $1.00 supply is all you’ll need for the whole season.
Dissolve the fungicide in water, according to the directions on the box, and sprinkle on the plants with a watering can. Natriphene is available from the Natriphene Co., 424 Book Bldg., Detroit, Mich.
44659 by Carl Grant Wilson